Method for making air-cooled cylinders



March 5, 1946. A. vANG 2,396,216

METHOD FOR MAKING AIR COOLED CYLINDERS -Filed April 5, 1943 WELDING OUTFIT DISTRIBUTOR lNSULATIUN y lINVENTR. @fl' ALFRED VN BY MV i.

Patented Mar. 5, 1946 2,396,216 .mamon Fon MAKING Am-cooLnn crLmnEas Alfred Vang, Newark, N. J., assigner of one-half to Stevenson, Jordan & Harrison, Inc., New York, N. Y., a corporation of New York Application April 3, 1943, Serial N0. 481.722

2Ciaims. (Cl. 21S-10) A This invention relates to new and useful improvements in a method for constructing aircooled cylinders for engines, refrigerator systems,

heating systems, and other purposes. Thus, it may in like manner be applicable to any hollow object to which it is desired to impart the characteristics of my invention.

While this speciication willbe directed to an internal combustion engine, this should not be viewed as a limitation of the invention, but rather as an example and illustration.-

The main advantage gained with respect to an engine resides in greatly increasing the thermal elciency of the radiating system in said engine. This is very important because itthen becomes possible to increase the horsepower of air-cooled engines without any increase in weight. It is rather obvious what this will do in aviation. It will increase speed, flying distance, load carrying ability, and improve other characteristics of the airplane.

It may here be pointed out that with an increased thermal eiliciency of the radiating system of the engine, it becomes possible to operate the engine at a higher compression. Of course, more fuel will be consumed and more heat will be liberated. The extra consumption of the fuel will increase the horsepower of the engine. Thehigher temperatures will not, however, be detrimental because of the more efcient radiating system.

Fundamentally this new method for constructing an air-cooled cylinder consists in closely spot welding fin material of great thermal conductivity directly upon the steel cylinders of the engine. Preferably, this iin material will bekaluminum, as this material has a great conductivity constant at high temperatures. Other materials may also be used, such as copper. At relatively lower temperatures copper is a better conductor of heat, but at the high temperatures proposed for the improved engine, aluminum will be ideal.

In order to' properly understand this invention some consideration should now be given to the phenomenon of heat transmission. -Heat is propagated from one place to another by Uconduc-y tion in which the heat passes from one body-to another, or even from one part of a'bodyto another' by actual' contact.A The accepted theory of heat conduction is that the warmer molecules of the body impart heat to the colder ones; The transfer of'heat is .notstatic-but an active condition in which eachmolecule is absorbingv and radiating `heat atthe; same -time. The hotter molecules radiate moreheat energy than they absorb, and the colder ones absorb more than they radiate. The result is that there is a tendency for equalization of temperature, but even after the equalization of temperature has been reached-the processo! radiation and absorption continues. Y

When bodies are in physical contact with each other, as distinguished from molecular connection, there is always a illm between the bodies which have great heat resistant qualities. This illm may be one of oil, oxide, or other foreign impurities. It is a generally accepted theory that nlm of this nature accounts for of the difference in temperatures between contacting bodies which are at diiIerent temperatures and which are undergoing the transfer of heat from the hotter to the colder one, and in which a sufficient time has passed and yet the temperatures have not been equalized.

Bearing in mind the phenomenon of heat transmission, we are now ready to consider the prior methods and constructions of air-cooled cylinders. In one of these old constructions the nns were forged or by any other method made integral with the steel cylinders themselves. This method has long been discarded since steel is a relatively poor conductor of heat in relation to such metals as copper and aluminum. Even though the steel fins were integral with the steel cylinders, the thermal eiiiciency of the radiating system was poor, tending to cause the cylinders to become red hot and consequently requiring a cutting down of the number of explosions in a time interval and the pressures of these explosions. Engines having radiating systems thus constructed were consequently heavy in relation to the horsepower they produced.

An improved method was subsequently developed in which copper fins or fins of ,other good conducting-materials were shrunkv on tothe steel cylinders. 'I'his construction, however,ifalsoem bodied numerousinherent defects.- In the ilrst place the contact between the nsand thecylinder was poor, eventhough very. tight., -Anobjectionable film, such aspreviously, pointed out, alwaysl existed. 'This film in itself cut down the conduction of heat from the cylinder to the ilus.

Another important defect was that when the cylinder and ilns became heated they would expand different amounts,-and .under certain con'- ditions the iins would actually become loose and this, of course, further impaired'the efciency of thermal radiating system from the cylinder. While engines Q1 this type developed more horsepower than the previous types, they were soon further improved.

The latest improvements prior to the instant invention, included the actual welding or brazing of a binder material to the cylinder. and welding or brazing of fins to the binder material. This construction was a great deal better than the prior construction, but it is not at maximum emciency. The use of the binder material cuts down the eiliciency of the radiating system since it acts in the nature of a composite wall. While the welding or brazing process f theoretically places the molecules in molecular contact with each other, it is known that the maximum radiating efiiciency is not obtained because of the composite nature of the wall thus produced, which cuts down the conductive qualities. Obviously the molecules are not in tight connection with each other and the formation of a ccmposite wall thus interferes with the free transfer v of heat between them.

The reason that prior constructions made use of a binder was that no commercial method was known for directly welding fins of aluminum or other highly conductive material on to the steel cylinders. Spot welding of dissimilar metals was known, but the usual spot welding would not sufflee in this case because, then only, points of the dissimilar metals would be in molecular connection, while the remaining area would merely be in physical contact with. each other.

We may now understand the present invention by realizing that it covers a method for actually welding fin material of great thermal conduclftivity, such as aluminum (and others) to steel cylinders. The new and improved method essentially consists in an arrangement by which the spot welding may be so closely arranged that the weld will be substantially 100% continuous. It is only done at spots, but these spots contact and overlap each other, thus producing the continuous weld. In this Way a spot welding method is used for continuously welding the iin material to the cylinders.

The invention further proposes to characterize the new method by use of spot welding electrodes and an'arrangement for relatively moving these electrodes along the fin material and the cylinder, and to rapidly spot weld during this motion.

Still further, the invention proposes to arrange the fin material in the nature of a strip and to feed it spirally on to the cylinder, and during this feeding operation to move the spot welding electrodes relative to the n material and the cylinder to accomplish the close welding of these materials.

lWith the above and other objects in View, this invention consists of the novel features of construction, combination, and arrangement of parts, hereinafter fully described, claimed, and illustrated in the accompanying drawing, forming part of this application, and in which similar characters of reference indicate corresponding parts in all views, and in which: A

l Figure 1 isa sectional view of one of the cylin ders of an air-cooled engine, embodying this invention.

vFigure 2 isfa fragmentary enlarged detailed view of a portion of Figure 1. but with a front portion of the cylinder being illustrated.

Figure 3 is a sectional -view of the cylinder 'shown in Figures 1 and 2," but illustrated in conjunction with .means for constructing the cylintdier with the fins in accordance with this inven- Figure 4 is a schematic view of the welding outt used in this invention.

In Figure 1, reference numeral I0 indicates generally the steel cylinder of an internal combustion engine. This cylinder is shown provided with a cylinder head I2. The cylinder is also provided with fins I3 for assisting in radiating the heat of combustion. The invention relates especially to the application of these tins I3.

In Figure 2 a detail is disclosed of the ilns I3. It should be noted that they are formed from a strip of material wound helically on the cylinder I0. This strip of material is substantially of L-shape in transverse cross section, so as to have an arm portion I3a which engages against the outside diameter of the cylinder III and a radially projecting arm portion I3b from which the heat radiates freely. The invention particularly proposes that the ilns I3 be made of aluminum or other material of great thermal conductivity. The invention relates to the welding of the iin material I3 to the steel cylinder I0.

In Figures 3 and 4 a detail has been shown oi the means for welding the fin material in position. The cylinder III is rotatively supported by an end Adisc I5 which is engaged in one end thereof. This end disc is mounted on a shaft I8 rotatively supported in a standard I1. A spring I8 urges the disc I 5 into the end of the cylinder I0.

A pair of friction rollers I9 and 20 frictionally engage opposite points upon one side of the cylinder I0. Specifically, the friction rollers I9 and 20 are located inside and outside of the cylinder I0. These rollers are mounted on the shafts 22 of a drive system 23 which is designed so that the cylinder I0 will be slowly turned.

A spot welding outfit 24. having a gang of electrodes 25 and 26 located inside and outside of a wall area of the cylinder IIJ, is arranged to closelyl spot weld the fin material I3 to the cylinder. 'I'he electrodes 25 and 26 have contact rollers 25a and 26a for engaging the work, and are supported by a support frame 21. One of the electrodes is disposed in the corner of the fln and one of the opposed electrodes is oflset so that a line joining the two substantially passes through the corner portion of the iin. This support frame 21 is resilient material so that the electrodes 25 and 26 may be properly pressed against the work being welded. The electrodes 25 and 26 are connected up with a distributor 28 which is driven by the drive means 23, so as to work simultaneously with the turning of the cylinder III. The distributor 28 has a rotating arm 28', which engages the contacts 3U and 3| in succession to close the electrical circuit to the individual electrodes of the gang of electrodes so that they work one pair at a time. The details of the spot welding outilt will not be given in this specification as it forms no part ot the invention and any type of outfit may be used. The type recommended would be like that disclosed in my invention covered by the U. S. Patent No. 2.287.544, issued June 23, 1942, and entitled "Electric welding of metals and the uniting of dissimilar metals.

The operation of the device is as follows:

The fin material I 3 may be drawn oiI from a supply spool, or supplied in any other desirable Way. It is helically wound on the cylinder III in the manner illustrated in Figures 2 and 3. It may be closely spotwelded as .it is helically wound on the cylinder, or it may be subsequently spot welded after it has been placed in position.

The spot welding operation must be carried out as follows: The gang of electrodes 25 and 2B is started at one end o! the iin material I3. The cylinder I slowly rotates ,and the gang of electrodes move longitudinally along the helical formation. During this motion the electrodes individually spot weld points of the iin material and v'the cylinder. These points must be very closely spaced together. In fact, they must be so closely spaced that they overlap. This welding operation may be carried on in one operation, or the spot Welding may be carried on in more than one operation. When the latter system is used the spot welding initially is not spaced so closely, but then a second series 0i spot welding is done in between the points of the first group of spot weldings. In this way the fin material i3 is closely spot welded, in fact, so closely spot welded that it is substantially 100% welded to the cylinder I0.

It is pointed out that the fin material i3 is directly welded to the cylinder i0. There is no intermediate third material to form a binder between them. As pointed out in my prior patent the spot Welding operation breaks through the film on the contacting surfaces of the materials being spot welded. Thus the objectionable ilhn which hinders the conduction of heat is broken up, and the molecules of the fin material will be in molecular contact with the molecules of the cylinder. l When this is so, there will be free conduction of heat from the cylinder I0 to the ns i3.

It will be found that the thermal eiilciency of the radiating system of the cylinder when constructed in accordance with this invention will be some 27% higher than with the past prior construction. Because of this, the engine may be designed to produce more horsepower per unit of weight. The advantages of this have already been discussed in the object portion of this specimation.

It is obvious that slight changes may be made the appended claims, without departing from the spirit of my invention, and I do not, therefore, wish to limit myself to the exact construction and arrangement shown and described herein.

The apparatus disclosed herein forms the sub ject matter of my application, Serial No. 513,885, iiled December 11, 1943.

Having thus described my invention, what I- claim as new and desire to secure by United States Letters Patent is:

1. A method for providing hollow steel cylinders with fins, said method comprising helically winding metallic strip material of L-shaped cross section on and around the exterior face of the cylinder, the base of the strip of each turn being applied ilat against said face, and applying high frequency, high voltage current to a turn and a cylinder between a point at the inside corner of the strip and the point where the shortest line passing substantially through the outside corner intersects the inner face of the cylindler.

2. A method for providing hollow steel cylinders wi-th iins. said method comprising helically winding metallic strip material of L-shaped cross section on and around the exterior face of the cylinder, the base of the strip of each turn being applied iiat against said face, and applying high frequency, high voltage current to a turn and the cylinder between a point at the inside corner of the strip and the point where the shortest line passing substantially through the outside corner intersects the inner face of the cylinder; the application of said current being intermittent and at points progressively along the turns to form a series of spot welds, so closely spaced as to substantially overlap.

ALFRED VANG. 

